The present invention relates to a torque feedback shift control device and method, and more particularly to a torque feedback shift control device and method designed to reduce torque fluctuation (shift shock) occurring in shifting in a vehicle with an automatic transmission.
A control device for reducing shift shock is disclosed, for example, in Japanese Patent Laid-open No. 63-254256, wherein an input speed of an automatic transmission (an output speed of a torque converter) becomes an input speed for determination of shift start, so that engine output reduction control for reducing the shift shock is started. Another control device for reducing a shift shock is known from Japanese Patent Laid-open No. 64-4544, for example, wherein it is determined whether or not a shift command is present, and if so, a gear ratio is computed from input and output speeds of an automatic transmission and shift start is determined according to the gear ratio computed.
In the prior art mentioned above, engine torque control and timing control are performed in accordance with a predetermined look-up table provided for each shift position, thereby reducing shift shock in shifting. In such control, engine output is controlled to a value that is predetermined for every operational condition of the transmission; and hence the engine torque can be reduced only by a fixed quantity. Accordingly, it is necessary to preset various control quantities corresponding to various conditions to be considered. As a result, various parts must be tuned, requiring much time and labor and making a complete reduction in shift shock difficult